I don't have any college level statistics or math knowledge. However, I think it might be important to put in my layperson's observations into text.
What Professer Pi suggests is a more complicated formula for determining someone's level, to address certain perceived inequities in the currect XP/Writeup level system. Another user points out a potential inequity in that system, and proposes a more complicated formula for determining a user's level. Another user points out a potential inequity in that system.
Logically, every system is going to have some kind of inequity. The more complicated system we use, the more complicated the inequity, and the harder it will be to spot them.
Eventually, we have a system that the average noder can't figure out. Maybe a program like the E2 Node Tracker will be able to tell them their WasdfGTKY^2WhateverNode-Foo is too low, but they'll have to find a math or statistics geek to tell them how much they have to improve their nodes to level up.
Now, admittedly, I kinda follow Professor Pi's formula. The other suggestion I'd probably have to go over a few times, and may have to use some references to figure out. But the more complicated we make the system, the harder it's going to be to quantify how "good" or "bad" we're doing. Obsurity in advancement (or lack thereof) can be very discouraging, and cause us to lose what might otherwise be quality noders, or people who could become quality noders if they could understand the advancement system. Admittedly, gaining levels (and the associated perks) are a HUGE incentive to write better nodes. I'd like more of my nodes to have a higher rep than they do now.
There is also the problem of subjectivity, not of the content of a writeup, but of the perception of those who upvote or downvote a writeup. I have a lyric node that is at -4 rep right now, simply because of the title and lyrics. Why Won't Jesse Helms Just Hurry Up And Die? is a factual representation of the lyrics of a song that has widely circulated the net. As of this writing, 8 upvotes and 12 downvotes. I never understood how a lyrics node could get downvoted, aside from a total lack of html tags to format the text (which my writeup doesn't suffer).
I also see the possiblility, with some of these formulas, of a flood of E2 Nuke Requests when people decide they want to get rid of their low reputation writeups to advance a level.
Just my 2.32 Yen (approx 2 cents) worth.